In the related art, a game which may use a character which has been leveled up or grown in strength in the game by a user is known. For example, Japanese Patent No. 5,819,510 discloses a game which is played by a user by borrowing a character of another user.
However, in the game in which a character of another user is borrowed, since powers of characters may be different depending on the users, it may be difficult to adjust game balance. For example, when a user not owning a powerful character plays a game by borrowing a powerful character owned by another user, the game may decline in difficulty. Accordingly, there is room for improvement in adjustment of game balance.